David Wilson on Phil Davis on Meta Analysis of the OA Impact Advantage

"I don't know enough about this area to ascertain the credibility of [Phil Davis's] criticism of the methodologies of the various studies involved. However, the one study that [Phil Davis] claims is methodologically superior in terms of internal validity (which it might be) is clearly deficient in statistical power. As such, it provides only a weak test. Recall, that a statistically nonsignificant finding is a weak finding -- a failure to reject the null and not acceptance of the null. Meta-analysis could be put to good use in this area. It won't resolve the issue of whether the studies that Davis thinks are flawed are in fact flawed. It could explore the consistency in effect across these studies and whether the effect varies by the method used. Both would add to the debate on this issue."